Process for dehydrating alcohols and other organic compounds



Patented Aug. 23, 1932 UNITED. STATES PATENT- OFFICE SYLV AN R. KEELEY, OI DOVER, NEW JERSEY, ASSIGIIOB '10 DOHEBTY RESEARCH OOH- IANY, OF NEW YORK, N. Y., A CORPORATION OF DELAWARE rnocnss ron. n'nmnarme amonorls AND orrmn onemrc como't'mns 10 Drawing.

The present invention relates to a process for dehydrating alcohols and other organic compounds such as esters produced from pctroleum hydrocarbons. The process is ar- Y ticularly adapted for the dehydration o the higher secondary and tertiary alcohols as wellas the esters of such alcohols.

Since manyof these organic compounds form constant boiling or, are very diificult to dehydrate because of being hygroscopic or because they decomigplse on distillation, they cannot be success y treated by ordinary methods.

The primary object of the present invention is therefore, to eificiently remove the water from such compounds by a-rapid and inexpensive process.

In accordance with this object the water is separated from the alcohols or other compounds by the use of a third liquid in a distilling operation, comparable to that disclosed in the German'paterit to Dr. Konrad Kubierschky issued in 1915, No. 287,897.

' A further object of the invention is the provision of a processof dehydrating oxygen containing hydrocarbon compounds in which use is made of a Water carrier liquid of abnormal water carrying power and which at the same time is very inexpensive.

In accordance with this feature of the process it is proposed to use a petroleum byproduct, which heretofore has had practically no commercial value and whichhhas 21. water carryin "ca acity many times t at o reviously ki iowh liquids such as benzol. p

Various methods for dehydrating alcohols, particularly ethyl and propyl alcohol, have .been proposed in which a third liquid such" as benzol is added to an alcohol-water mixtureand the final mixture subjected to distillation so that a ternary .constant boiling mixture is formed and distills'over' at a lower temperature than the boiling point of the alcohol. Such processes are illustrated for example, by the German patent referred to above and the U. S. patent to Stefiens No.

The theory and practice upon which these processes proceed is that a ternary mixture must be formed and that the ternary mixture mixtures with water Application filed Kay 23, 1828. Serial No. 280,119.

over contains a higher ratio of wa- I ter to alcohol than the original alcohol-water mixture.

One of the outstanding drawbacks tothese processes however, is that the amount of alcoder to remove a comparatively small quantity of water.

While-th' process of the present invention may be carried out in apparatus similar to that shown in the patents referred to, it is preferred to operate on a comparatively large batch of mixed alcohols in a still equipped with a rectifying column. Such a mixture of alcohols is obtained by the hydrolysis of a mixture of alkyl sulfates, which in turn has been produced 'by reacting 'onpetroleum productscontainingolefins, with concentrated sulfuric acid. This process of obtaining alcohols is well known and need not be de-. scribed in detail. It is sufiicient for present purposes to know that thewet alcohol mixture comprising the raw material for the present process comprises a mixture of alcohols such as isopropyl, isobutyl, secondary butyl, the amyl alcohols (secondary and tertiary), the hexyl alcohols and other higher secondary and tertiary alcohols. This crude mixture after. distillation from the hydrolyzed material and before being subjected to the present treatment contains from 10 to 15% walten.

The water carrier to be used in the proces of dehydrating this mixture of alcohols is a polymer which can be obtained from, and which comprises a light fraction of what is commonly known in the industry as 66X;

In the treatment of petroleum products 0011- taining olefins/ with 66 B. sulfuric acid for quantities of polymerized substances are is thepolymer known as 66X, and is usuthe production of alkyl sulfates considerable jp'e'rature with water of from 50 to 70 C. -A

ally discarded as a waste product. The fraction of 66X used in the present instance is a clear. mobile liquid havlng a boiling temquantitative analysis'of this fractional poly mer product has not been made'but from a qualitative analysis it is known to contain low boiling ketones (such as acetone) ,polymerized olefins (such as diisobutylene), light saturate ed hydrocarbons and sulphur derivatives of. unknown composition.

. of sulfuric acid on an olefin for the formation of polymers may be illustrated as follows:

Dl-llobntylene or iso-octylene The di-isobutylene present in the polymer water'carrier may also be formed durin the hydrolysis of the acid alk'yl sulphate hquorby the dehydrating action of 'sulphuricacid on tertiary butyl alcohol. The process may-be carried out as follows:

To a charge of about 10,000 gallons of mixed wet alcohols in-the-still is added from to '75 allons of the polymer water carrier dcscrlbed above. The mas is heated by means of steam coils or other suitable means and the vapors subjected to rectification inthe column so that the vapors of the polymer water carrier'and water will be carried over from'th'e column.

t 'A condenser and separator are provided for condensing the polymer-water vapors.

and allowing the condensate to separate into two layers-v The polymer is substantially immiscible with .water and of lighter gravity, so

that as it forms into a layer in the separator it is returned to the still to carryover addi:

tional quantities of water: It is preferredto 7 return the polymer layer direct tothe' still,

at least until practically all of the water has been removed from the alcoholjnixture, since this obviates the necessity of such high temperature in the still. desirable to introduce part of the return polymer into the column to control the temperature or-provide reflux.

' As long as there is any appreciable quan- However, it may be.

tityof water in the alcohol mixture only a very small proportion of alcohol is carried over with the polymer and water; in fact, the first portions of the water separated are discarded'as not containinvalcohol sufiicient to warrant its recovery. Eben in the latter part of the distillation the most of the alcohol carried over and condensed is returned to the stiIl'or tower because of its solubility in the polymer layer. As'long as there is any water in the mixture in the still two layers will be formed in the separator, so that as soon as the look box for the separator shows but a single layer of condensate the batch of alcohols is completely dehydrated. V

- The water having been separated from the alcohols the distillation is continued until substantially all of the polymers'are driven over, condensed and conducted to stora e to be used for a subsequent batch'of alco ols.

. It will be noted that because of the relatively low boiling point of the polymer it is very readily separated from the alcohols; isopropyl the lowest of .the series boiling at 823 C. In this separation there is no difliculty from the formation of binary or ternary constant boiling mixtures between the polymer and, the alcoholsas in the case of benzol. While the polymer may form a constant boiling mixture with the water inthe .water-alcohol mixture its carrying power maybe explained'by assuming that in distilling a mixture of alcohols and. polymer, the olymer steam distils much more readily t an the alcohols. Inother words thereis a selectivesteam distillation of the polymer in preference to that of the alcohols.

The polymer water carrier has a much greater water carrying power than has been noticed with any other compound. In some cases'the amount of water carried over in the vapors has been as high as 50%'while at other times the amount has been as .low as 30%. These difierences may be accounted for by the fact that a-difl'e'rent polymer was used in the different instances; that is, the polymer'used at one time was produced in a different sulturic acid treatment than that used at another time. w

carefully regulate the amount of'the third liquid introduced into the distilling mixture in order to avoid contamination of the deb drated. alcohol, because the third liquid formed a constant boiling binary mixture with thealcohol. No such difliculty has been experiened'inusing the carrier liquid described above. In batch distillation it is of course desirableto eliminate the polymer along'with the last traces of vwater so that at the close of the dehydration ste After the water and polymer ave been removed from the alcohol mixture, the mixonly a small amount remains to be removed way to separate out the various alcohols. This fractionation may be carried. on in the still where the previous dehydration distillation has been carried onby merely passing each fraction from the separator to an individual receiver. It is preferred to fractionate the alcohol mixture after dehydration because a much'better separation can be made due to the absence of the water which in some instances changes the boiling temperature of the components and appears to render the cuts less distinctive,

While the process-has been described in connection with alcohols, particularly with a mixture of alcohols it is to be understood that the process is not to be limited to such treatment since it is equally applicable for the dehydration of individual alcohols, esters or other organic compounds. The process is especially useful in dehydrating mixed esters produced by the direct reaction between alkyl sulfates or halidcs and calcium, acetate or other esterifying agent. Where- I mixed alkyl sulfates are produced from olefin containing materials they may be hydrolyzed to alcohols or treated directly wlth an esterifying agent to produce esters. In order to purify the mixed esters steam distillation is necessary and either before or after fractionation'the esters must be dried. vWhere esters are dried by the above described process it is often unnecessary to make a clean separation of the polymer after the water has been removed, because esters are usually sold in the solvent-trade as esters. This tolerance of 15% may, therefore, be made up of polymer which in no wav interferes with the solvent properties of the esters.

Having thus described the preferred emis claimed bodiment of the invention what as new is: A

1. The process of re'moving water from a mixtureof aqlieous alcohols, which comprises adding a light petroleum pol. er liquid to said mixture, said polymer being of the type formed by the action of sulfuric acid on hydrocarbon material containing unsaturated hydrocarbons and substantially immiscible with water, distilling the resulting mixture to drive off the polymer and water, condensing the polymer-water vapors, separating the polymer from the water and constantly returning the polymer to the distilling zone until the water content of said alcohols is removed.

2. The process of re oving water from a mixture of aqueous alcohols, which comprises subjecting such a mixture to distillation with a liquid adapted to increase the ratio of water to alcohols in the vapors produced" in said distillation, above theirnormal distilling ratio, said third liquid comprising a low boiling fraction of a polymer formed in the manufacture of alkyl sulfates from olefin material and sulfuric acid.

3. The process of producing dry' alcohols from aqueous alcohols, which com rises mixing with the aqueous alcohol to dried a lower boiling petroleum polymer liquid of the type formed by thewaction of sulfuric acid on hydrocarbon material containing unsaturated hydrocarbons, said polymer having a greater aflinity for water than said alcohol, subjecting the mixture to distillation to drive over the water and added liquid and recovering the re ining dry alcohol;

4. In the process of dehydrating aqueous alcohols in which a third liqlfid miscible with the alcohol but substantially immiscible with water is added to the aqueous alcohol to be dehydrated and the mixture subjected todistillation to separate the third liquid and water from the alcohol, the improvement which comprises using as said third liquid a polymer produced in the treatment of olefin containing hydrocarbon material, with sulfuric acid and comprising a low boiling dis- 1 tillate having a-boiling temperature of from 50 to 70 C.

5. In the process of dehydratmg aqueous alcohols in which athird liquid miscible with water is added to the aqueous alcohol to be' dehydrated and the mixture subjected to distillation to separate the third liquid and water from the alcohol, the improvement which. comprises adding a third liquid adapted to carry over in the'distillation, water vapor equal to 30% of the total vapor, said liquid comprising a polymer formed from-olefin containing hydrocarbon material.

7. The pi'oc'ess of refining mixed aqueous alcohols, which comprises subjecting the aqueous alcohols to distilling conditions in the presence of a water stripping agent derived from polymerized olefin bearing materials, said agent being adapted to selectively remove water from said alcohols, distilling over and condensing the water and stripping agent, separating the agent fi'om the water and returning it to the distilling zone, and

from said alcohols continuing the distillation to remove and separate the remaining portion of-the stripping agent.

8. In the process of dehydrating aqueous after substantially all of the water is removed organic compounds containing oxygen, such' is alcohols and esters, in which a third liquid miscible with the organic compound but substantially immiscible with water is added to the aqueous compound to be dehydrated and the resulting mixture subjected to distillation to separate the third'liguid and water from the organic compoun the improvement which comprises supplying for said third liquid an organic polymer mixture of thetype formed by the action of sulfuric acid on hydrocarbon material containing unsaturated hydrocarbons. j In testimony whereof I aflix my signature.

. r SYLVAN R. MERLEY. 

